88% of U.S. Deaths From Hurricanes, Tropical Storms Are From Water, Not Wind

According to the National Hurricane Center (NHC), storm surge, rainfall flooding, high surf and deaths just offshore (within 50 nautical miles of the coast) combined for 88% of all deaths in the U.S. from hurricanes, tropical storms or tropical depressions from 1963 to 2012.

Deaths from a tropical cyclone's winds or embedded tornadoes accounted for only 11% of fatalities in the U.S. during that time.

This may sound counterintuitive since Category 1, 2, 3 hurricanes are rated based on their maximum sustained winds.

(MORE: Saffir-Simpson Hurricane Wind Scale)

Certainly, a hurricane or even a strong tropical storm is capable of wind damage.

The intense eyewall winds of Category 5 Hurricane Andrew destroyed over 25,000 homes and damaged 101,000 more in Homestead and the south Miami suburbs in August 1992.

Despite that devastation, 26 deaths – 15 in South Florida – were directly attributed to the hurricane.

Storm Surge: The Deadliest Threat

Roughly half of all U.S. deaths from tropical cyclones are due to the storm surge, the rise in water levels from the tropical cyclone's winds piling water toward the coast just before and during landfall.

Storm surge is not simply a function of the maximum winds.

Hurricane Ike was not a "major" (Category 3 or stronger) hurricane at landfall in Galveston, Texas, in September 2008. Yet the size of Ike's wind field generated a 15- to 20-foot storm surge that wiped out most structures on the Bolivar Peninsula of Texas.

Well before the modern age of satellites, television and instant communication, a storm surge of up to 15 feet, with battering waves, claimed most of the 8,000 to 12,000 lives lost in the Galveston, Texas, 1900 hurricane, the nation's deadliest.

To more clearly communicate the threat from storm surge, the NHC will prepare potential storm-surge inundation maps when a hurricane or tropical storm threatens the coastline.

These maps will identify how deep the storm-surge inundation may be above ground level in a worst-case scenario based on the forecast track, intensity and wind field.

Rainfall Flood Threat

Let's consider some examples to illustrate this threat.

Hurricane Florence in 2018 and Hurricane Harvey in 2017 are recent reminders of the dangers caused by a tropical cyclone's rainfall flooding.

Harvey loitered for days in southeastern Texas in August 2017, unleashing up to 60.58 inches of rain near Nederland, Texas – the heaviest rainfall total from any tropical cyclone in the U.S. on record – which resulted in massive flooding and 68 deaths in Texas alone.

(MORE: Before-and-After Images Reveal Houston's Disastrous Flooding From Harvey's Rainfall)

Just over a year later, in September 2018, Florence became the nation's second-wettest storm behind Harvey after it stalled over the Carolinas for days. Preliminary state rainfall records were set in both North and South Carolina. The highest total was 35.93 inches of rain near Elizabethtown, North Carolina, about 50 miles northwest of Wilmington.

Hurricane Irene in 2011 may be one of the most forgotten U.S. landfalls, given Superstorm Sandy was just a year later.

There was surge flooding along the coast from the Outer Banks of North Carolina to southern New England, but this storm wasn't just a coastal danger.

Irene's legacy was its epic inland rainfall flooding from parts of New York state into New England, particularly in Vermont, where almost 2,400 roads, 800 homes and businesses and 300 bridges were destroyed or damaged from the flooding.

Of the 41 total U.S. deaths attributed to Irene, 21 of those were from rainfall flooding.

Now, consider a system that wasn't officially a depression anymore when it inflicted its havoc.

Tropical Storm Allison in June 2001 soaked the Houston metro area as it made landfall, then dropped a massive second deluge when its remnants moved southward back over the Texas coast a few days later. Up to 37 inches of rain swamped parts of America's fourth-largest city.

This $9 billion tropical storm, the costliest tropical storm in U.S. history, claimed 41 lives in the U.S. Twenty-seven of those died from rainfall flooding.

Hurricane Agnes in 1972 was barely so at landfall, a Category 1 when it crossed the Florida Panhandle coastline. However, its final move and subsequent stalling over the Northeast triggered massive flooding. Of the 122 U.S. deaths, 113 were due to rainfall flooding.

The bottom line here is to respect the power of water in tropical cyclones. Don't become a statistic.